Tube forming machine



July 21, 1936. H. H. HENTZELL El AL TUBE FORMING MACHINE Filed Sept. 28, 1955 INVENTORS Howard A. Hemze/l atente July 23, I36

UNlTE STAT PATEE' oFFic TUBE FORMING MACHINE Jersey Application September 28, 1935, Serial No. 42.663

8 Claims. (01. 25-17) a This invention relates to plastic material working machinery and particularly to machinery for forming tubes from plastic material such as clay.

It has for one of its objects the provision of a 5" tube forming machine in which the bore of the tube will be true and accurate.

A further object of the invention is to provide a tube forming machine having a floating arbor for forming the bore of the tube, the arbor being automatically centered by the action of the plastic material.

A further object of. the invention is to provide a device of the class named which shall be of improved construction and operation.

Other objects and advantages will appear from the following description.

The invention is exemplified by the combination and arrangement of parts shown in the accompanying drawing and described in the following specification, and it is more particularly pointed out in the appended claims.

In the drawing:

Fig. 1 is a vertical sectional view of a portion of a tube forming machine having the present invention applied thereto. Y

Fig. 2 is an elevation with parts in section showing on a larger scale a part of the invention.

'In machines for forming tubes of clay or other plastic material, it has heretofore been the practice to extrude the clay through a nozzle by means of a screw propeller, an arbor being secured to the end of the propeller for forming the bore of the tube: In such devices, it is impractical to provide a bearing for the propeller in the nozzle so that the propeller projects into the nozzle from a bearing at its rear end. This requires considerable overhang for the propeller shaft and makes it almost impossible to avoid slight eccentric motion of the shaft axis during operation of the device. This eccentric motion has heretofore been imparted to the arbor and since the plastic material has an axial movement through the nomle, the result is the formation of a helical groove in the interior of the tube; usually referred to as rifiing. By the present invention the arbor is antomatically centered and the eccentric motion is avoided, thus eliminating this rifling operation. which is'objectionable in some forms of tubes. particularly porcelain tubes for electric insulation.

In the drawing, the numeral I ll designates the outlet nozzle of a pug millfor porcelain clay or other plastic material, the material being fed the propeller screw l2 and fed outwardly through the nozzle by means of helical bla IS. The outlet end of the nozzle is provided wi h a ta red portion M which compresses the clay as it enters the outlet orifice IS. The propeller shaft I6 is carried in a bearing il in the rear of the nozzle, the end of the shaft being tapped to receive the threaded end l8 of an extension bar I9 to which the floating arbor is secured by means of an interposed link 2| and a pair of universal joints Hand 23. The link 2| has balls 24 and 25 integral with its opposite ends, the balls being held in sockets in the bearing members 22 and 23 by closure discs 26 and 21 which form ball recesses for ball bearings 28. The arbor 20 has a die 29 mounted thereon and held in place by lock nuts 30. I he die preferably has a conical portion 3l facing the outwardly moving clay to facilitate movement of the die through the clay. However, the moving clay will accumulate on uneven portions of the arbor and automatically form a stream line surface for the passing material. It will be seen that the link 2i and the, universal joint connections with the shaft and arbor provide a floating support for the arbor, which permits it to assume a position in the orifice is controlled by the force exerted upon the die 29 by the moving clay. It has been found in practice that the pressure of the clay automatically centers the die in a position co-axial with the orifice so 7 that the resulting tube has acontinuous uniform bore accurately centered relative to the wall of thetube, which is of uniform thickness, and'the rifiing of the bore of the tube produced by previous machines is entirely avoided. A single flexible joint in the connection between the end of the shaft and the arbor results in centering of the die relative to the orifice, but if the end of the shaft has a slight eccentric motion, this will result in tilting of the axis of the die although the main body of the die may be accurately centered relative to the orifice. This tilting motion of the axis of the die is overcome by the double universal joint, which not onlypermits the die to center itself automatically relative to the orifice but also permits the axis of the die to maintain a position coinciding with the axis of the orifice.

The clay or other plastic material passing through the nozzle in some cases has a rotary motion, due to the rotation of the propeller, which rotation may also be imparted to the die 29. The ball bearings 22 and 23 permit free rotation of the die 28, thus avoiding any tendency to twist of! the connection between the die and the shaft.

' l. A tube forming machine comprising a nozzle having a discharge orifice, a die for forming an opening in plastic. material forced through said orifice, and means for holding said die against the pressure of the material moving through said orifice, said holding means providing for free movement of said die transverse to the axis of said orifice under the force exerted on said die by said plastic material.

2. A tube forming machine comprising a nozzle having a discharge orifice, a die for forming an opening in plastic material moving through said orifice, and a flexible member for holding said die against movement in the direction of the movement of said plastic material but providing for movement transverse to said direction.

3. A tube forming machine comprising a nozzle having a discharge orifice, a propeller for moving plastic material through said nozzle, a die for forming an opening in the material moved through said orifice, and a flexible connection between said propeller and die for holding said die against movement in the direction 'of movement of said material but permitting transverse movement thereof.

4. A tube forming machine comprising a nozzle having a discharge orifice, a screw propeller for moving plastic material through said nozzle, said propeller being mounted on a shaft having its axis extending in the direction of the axis;

of movement of said material, a die disposed in said discharge orifice, and a flexible tension member connecting said die with said propeller shaft.

comprising a link and flexible connections at the opposite ends of said link with said die and shaft respectively. v

6. A tube forming machine comprising a nozzle having a discharge orifice, a screw propeller for moving plastic material through said nozzle, 5 the propeller being mounted on a shaft having its axis substantially in alignment with the axis of said orifice, a die for forming a central opening in the material passing through said orifice, and a tension member connecting said die with the end of said shaft, said tension member comprising a link having universal ball bearing connections at the opposite ends thereof to provide for rotation of said die upon its axis and for transverse movement of the end of said shaft 15 relative to the axis of said die while the axis of said die remains stationary. I

'7. A tube forming machine comprising a nozzle having a discharge orifice at one end thereof and a bearing at the opposite end thereof, a 20 shaft supported in said bearing and extending into said nozzle, a screw propeller carried by said shaft, a die disposed in said nozzle for forming a central opening in plastic material forced through said nozzle by said propeller, and a ten- 5 sion member connecting said die with the end of said shaft, said tension member comprising a link having universal ball bearingconnection at opposite ends thereof with said shaft and die respectively for holding said die against move- 30 ment in the direction of the movement of the plastic material in said nozzle while providing for rotation of said die upon its axis and for transverse movement of the end of said shaft relative to its axis while the axis of said die remains stationary.

HOWARD H. HENTZELL. ALBERT M. MORRIS. 

